PT827690E - QUANTITY AMMONIUM IONEN POLYMERS CONTAINING SULFUR AND THEIR USE AS MICROBICIDES - Google Patents

Abstract

A microbicidal composition comprising an aqueous solution containing a sulfur-containing quaternary ammonium ionene polymer comprising a repeating unit of formula II: <CHEM> wherein X &upbar& is a counter-ion; R<1> and R<2>, which can be the same or different, are selected from a lower alkyl group and -CH2-CH2-OH; A' is a radical selected from -S-, -S-CH2-CH2-S-, -S-S- and the oxidation products of -S-, of -S-CH2CH2-S- and of -S-S-; and B is a radical selected from C1-C5 alkyl, -CH2-CH(OH)-CH2-, and -(CH2)m-O-(CH2)m-, where each m is independently 1,2, or 3, and wherein said sulfur-containing quaternary ammonium ionene polymer is present in an amount effective to inhibit the growth of at least one microorganism.

Description

DESCRIPTION OF THE QUANTITY OF AMMONIUM IONEN POLYMERS CONTAINING SULFUR AND ITS USE AS MICROBICIDES &quot; The invention relates to sulfur-containing quaternary ammonium ionene polymers and to their use as microbicides. Microbicidal compositions and methods for inhibiting the growth of microorganisms using sulfur-containing quaternary ammonium ionene polymers are also described.

Description of the Invention

Described herein is the use of sulfur-containing quaternary ammonium ionene polymers as microbicides in the treatment of waters and surfaces. These polymers according to the invention may have lower toxicity to fish than other ionene polymers which are already marketed as water treatment chemicals.

A large number of commercial, industrial, agricultural and wood products are subject to microbiological attack that reduces or destroys their economic value. Examples of materials that may be subject to microbiological degradation are surface coatings, wood, agricultural seeds, leather and plastics, including flexible plastics. The temperature at which these products are stored and their intrinsic characteristics make these products susceptible to the growth of microorganisms. These micro-organisms may be introduced during the manufacture of these products by exposure to air, tanks, piping, equipment, and humans and / or during their use from 1 L,

N Multiple openings and closures of packaged products and the introduction of contaminated objects to shake or remove material.

Aqueous systems containing organic materials are highly susceptible to microbiological attack. Such aqueous systems include latexes, surfactants, dispersants, stabilizers, thickeners, adhesives, starches, waxes, proteins, emulsifying agents, detergents, cellulose products, agricultural irrigation fluids, and resins formulated in aqueous solutions, emulsions or suspensions.

These systems often contain relatively large amounts of water making them in environments well suited for microbiological growth and thus attack and degradation. Microbiological degradation of aqueous systems containing organic materials manifests itself in the form of a variety of problems, such as loss of viscosity, formation of gases, degradable odors, decreased pH, destruction of emulsions, color changes, and gelling.

Another adverse phenomenon that occurs in industrial process systems involving water is the formation of sludge. The sludge consists of plaited deposits of microorganisms, fibers and debris. It may be filamentous, pasty, rubbery, tapioca-like, or hard, and may have a characteristic undesirable odor which is different from that of the liquid suspensions in which it is formed.

Microorganisms mainly involved in the formation of sludge are different species of sporulating and non-sporulating bacteria, in particular encapsulated forms of bacteria secreting gelatinous substances that surround or enclose the cells. Slime microorganisms also include filamentous bacteria, mold-like filamentous fungi, yeasts, and yeast-like organisms. Sludge reduces the yields of 2 L · Lc, in papermaking and causes clogging and other problems in aqueous systems.

In addition, different types of water, both potable and brackish, need disinfectants to keep them from contamination by microorganisms. In the United States, the most common method of disinfection is the use of chlorination. Chlorination, however, can be accompanied by some disadvantages, such as chlorine gas explosion or leakage, during the treatment of water, and may result in the formation of toxic halocarbons, such as chloroform and the like. In this regard, various compounds are used as substituents for the treatment with chlorine, including ozone, chlorine dioxide, bromine, potassium permanganate, p-chlorosulfamidobenzoic acid, cyanuric acid derivatives, isocyanuric acid derivatives, quaternary ammonium compounds, and various chloramine compounds.

The quaternary ammonium ionene polymers belong to a class of compounds which, together with methods for their preparation, are described in U.S. Patent Nos. 3,874,870, 3,931,319, 4,025,627, 4,027,020, and 4,506,081, as well as the references cited in these patents. These polymers are often used as microbicides.

Certain sulfur-containing ammonium ionene polymers containing sulfur and methods for preparing them are also known. US Pat. No. 4,046,750 describes an ionene polymer containing a sulfur diradical, -S-, which is used to modify polymer beads for use in the attachment of a diversified group of small and large anionic compounds in diagnostic, analytical, separation applications and clinics. U.S. Patent No. 4,217,914 discloses sulfur-containing quaternary ammonium ionene polymers having divalent 3R L- containing sulfur, -S-, -S-S-, -so- and -SO 2 - radicals and their use in cosmetic compositions.

It is an object of the present invention to provide a microbicidal composition using a sulfur-containing quaternary ammonium ionene polymer as an active ingredient. Providing a method for inhibiting the growth of microorganisms in aqueous fluid systems or surfaces using a sulfur-containing quaternary ammonium ionene polymer is also an object of this invention. Other objects of this invention will become apparent from the description of the invention below or from the practice of the invention.

These and other objects may be made by: a microbicidal composition comprising an aqueous solution of a sulfur-containing quaternary ammonium ionene polymer comprising a repeating unit of formula II: &quot; ] -B-N-B-A-B-

R (II) wherein X- is a counterion; R 1 and R 2, which may be the same or different, are selected from a lower alkyl group and -CH 2 -CH 2 -OH; A 'is a radical selected from -S-, -S-CH 2 -CH 2 -S-, -S-S- and the oxidation products of -S-, -S-CH 2 CH 2 -S- and -S-S-; and B is a radical selected from C 1 -C 5 alkyl, -CH 2 -CH (OH) -OH 2 - and - (CH 2) m -O- (CH 2) m wherein each m is independently 1, 2 or 3 in an amount effective to inhibit the growth of at least one microorganism; 4 V and

a method for inhibiting the growth of at least one microorganism in an aqueous system comprising the step of adding to an aqueous system known to be in need thereof in an amount effective to inhibit the growth of the microorganism of the sulfur containing quaternary ammonium polymer comprising a repeating unit of formula II, above; a method for inhibiting sludge formation in an aqueous system comprising the step of adding to an aqueous system known to be in need of such inhibition of a sulfur-containing quaternary ammonium polymer comprising a repeating unit of formula II, above; and a method for inhibiting the growth of microorganisms on the surface of a substance comprising the step of surface application known to be required of such inhibition of a sulfur-containing quaternary ammonium polymer comprising a repeating unit of formula (II) above.

Best Mode for Carrying Out the Invention

Certain sulfur-containing quaternary ammonium ionene polymers comprise a repeating unit of formula I:

R

R. 2X-N-CH2 CH2 -N-CH2 CH2-a-CH2 CH2 -

R

R (I) wherein X- is a counterion; r and R 2, which may be the same or different, are selected from a lower alkyl group and -CH 2 -CH 2 -OH; and A is a radical selected from -S-, -S-CH 2 CH 2 -S- and the oxidation products of -S-, and -S-CH 2 CH 2 -S-. 5

(I.e.

II Ο counterion, X-, may be a monovalent anion or 2X- may be a divalent anion. Preferably, X "is a halogen anion; more preferably, chloride.

The substituents R 1 and R 2 are lower alkyl groups or -CH 2 CH 2 OH, preferably C 1 -C 4 alkyl groups. Most preferably, these substituents are methyl or ethyl groups. As used herein, and throughout this specification, the term &quot; alkyl &quot; includes both straight and branched chain alkyl groups. A is a radical selected from -S-, -S-CH 2 CH 2 -S- and the oxidation products of -S-, and -S-CH 2 CH 2 -S-. The oxidation products of the sulfur containing radical A are the products obtained by oxidation of the sulfur atoms within each radical. For example, the oxidation products resulting from the oxidation of an ionene polymer wherein A is -S-, are ionene polymers wherein A is -SO- after a first oxidation and wherein A is -SO2- after a second oxidation . As described below, it is possible to control the amount of oxidation to obtain ionene polymers having the sulfur atoms within the sulfur containing radical A in a desired oxidation state. The sulfur-containing radical A is preferably -S-, -SO-, or -SO2- and more preferably -SO- or -SO2-. The molecular weight of the sulfur-containing quaternary ammonium ionene polymers preferably ranges from 1,000-5,000, more preferably 1,000-3,000 and most preferably 1,500.

In a preferred embodiment, X is chloride; R 2 and R 2 are each methyl; A is -s-, -SO-, or -SO2 -; and the polymer has a molecular weight of about 1,500. 6

V,

In general, sulfur-containing ionene polymers of formula I may be prepared by reacting a suitable tertiary bis diamine, such as tetramethylenediamine (TMEDA), with a suitable dihalogenalkyl sulfide, eg 2,2'-dichloroethyl sulfide, a preferred temperature of 50 ° -90 ° C, more preferably about 60 ° C, for several hours in water. The reaction may proceed neatly without formation of by-products to advantageously provide a polymer-in-water solution which can be used as such or diluted to an appropriate concentration. In this case, no additional treatment is required.

To obtain quaternary ammonium ionene polymers containing sulfur radicals in which the sulfur atoms are oxidized, the solution of the ionene polymer product is oxidized by means known in the art, such as by reaction with hydrogen peroxide. The degree of oxidation is controlled by the stoichiometry of the reaction. The completion of the oxidation can be monitored by tests for the presence of peroxide as are known in the art, such as the starch / iodine test. This oxidation reaction also takes place neatly by giving a polymer-in-water solution which can be used as such or diluted to an appropriate concentration without further treatment.

An alternative preparation for oxidized sulfur containing quaternary ammonium ionene polymers is to react a suitable tertiary bis diamine with an oxidized dihalogenalkyl sulfide, such as the sulfoxide described by Yu-Chu Yang et al., J. Org. Chem. , 1990, 55, 3664-66. This preparation, starting from the oxidized dihalogenoalkyl sulfide, is carried out in the same manner as described above for the reaction between a tertiary bis diamine and a dihalogenalkyl sulfide described above. The present invention is therefore directed to the use as microbicides of novel ionene polymers of formula I, and other

V

sulfur-containing quaternary ammonium ionene polymers, all of which consist of the repeating unit of formula II:. 2X &quot; -B-N1-B-A &quot; -B-

R (II)

In these polymers, X 1, R 1 and R 2 are the same as defined above for the repeating unit of formula I. A 'is a radical selected from -S-, -S-CH 2 CH 2 -S-, -S- and of the oxidation products of -S-, -S-CH2CH2-S- and -SS-. Oxidation products may be obtained in the same manner as those of formula I. Preferably A 'is -S-, -SO-, -SO 2 -, or -SO 2 -S- and most preferably -SO- or -SO 2 -. The preparation of some sulfur-containing quaternary ammonium ionene polymers of formula II wherein A 'is -s-, -S-S-, -SO-, -SO 2 - is described in U.S. Patent Nos. 4,217,914. B is a radical selected from C 1 -C 5 alkyl, -CH 2 -CH (OH) -CH 2 -, and - (CH 2) m -O- (CH 2) m - wherein each m is independently 1, 2 or 3. Preferably , B is a C1-C3 alkyl and more preferably an ethyl group. The molecular weight of the ionene polymers preferably ranges from 1,000-5,000. A most preferred range is 1,000-3,000. Most preferably, the molecular weight is about 1,500.

The sulfur-containing quaternary ammonium ionene polymers of the present invention are effective microbicides against microorganisms such as bacteria, algae and fungi. There were found 8

that the sulfur-containing quaternary ammonium ionene polymers are particularly useful for inhibiting the growth of microorganisms in aqueous systems. Thus, the present invention relates to a method for inhibiting the growth of at least one microorganism in an aqueous system comprising the step of adding to an aqueous system known to be required such inhibition of a sulfur-containing quaternary ammonium ionene polymer in an amount effective for inhibit the growth of at least one microorganism. Representative aqueous systems include aqueous solutions, emulsions and suspensions as described above. Specifically preferred systems are metalworking fluids.

It has also been found that sulfur-containing quaternary ammonium ionene polymers are useful for inhibiting sludge formation in an aqueous system. Thus, the present invention also relates to a method for inhibiting sludge formation in aqueous systems comprising the step of adding to an aqueous system known to be in need of such inhibition of a sulfur-containing quaternary ammonium ionene polymer in an amount effective to inhibit the formation of sludge. This method is effective in aqueous systems such as a slurry of pulp or liquids used in water cooling devices.

A further use of the sulfur containing quaternary ammonium ionene polymers according to the present invention resides in a method for inhibiting the growth of at least one microorganism in a substance susceptible to deterioration or disfiguration by microorganisms or metabolic products of the microorganisms. The method comprises the surface admixture step admixed as required or mixing with the surface-forming substance of a sulfur-containing quaternary ammonium ionene polymer in an amount effective to inhibit the growth of at least one microorganism. This method is effective in substances such as wood, surface coatings (i.e., paint films), leather, agricultural seeds,

V U Artificial or naturally occurring polymers (including flexible plastic) and the like. This method for inhibiting the growth of microorganisms on surfaces achieves the desired inhibition over a significant period of time. Microorganisms whose growth is inhibited include, for example, fungi. In addition, the sulfur containing quaternary ammonium ionene polymers described herein are effective contact disinfectants. The present invention also relates to biocidal compositions comprising an effective amount of a sulfur-containing quaternary ammonium ionene polymer in an aqueous solution. The biocidal composition may contain other additives such as surfactants and antifoams, for example, as are known in the art. A biocidal composition containing a sulfur containing quaternary ammonium ionene polymer may be used in any of the methods described above.

According to the present invention, inhibition of growth of at least one microorganism or sludge formation comprises the prevention, control and / or reduction of such growth or formation. Thus, for example, inhibiting the growth of at least one microorganism in an aqueous fluid can be achieved by first preventing such growth, preventing or controlling further growth if it has already occurred, and / or by reducing the amount of any existing growth. The use of sulfur-containing quaternary ammonium ionene polymers as microbicides has several advantages. They are stable to hydrolysis over a wide range of pH, i.e., pH 3-11. They are also soluble in many solvents, such as water, short chain alcohols and some polar organic solvents, and therefore can be readily diluted for convenience of use, their compatibility, poor color, and efficacy makes them advantageous for use as microbicides in artificial polymers or of 10

V

natural occurrence and for impregnation or application on surfaces such as wood, paper, or other materials.

The sulfur-containing quaternary ammonium ionene polymers may, of course, be applied in a variety of ways - incorporated into a coating or composition, applied as powders by mixing with powdered diluents, dissolved in a solvent or in water and then emulsified and dispersed in a non- solvent. The particular desired use will generally dictate which method of application. The effective amount or percentage of active compound required to achieve the desired result will vary in some way depending on the substrate to be protected, the conditions for growth of algae, bacteria or fungi, and the desired degree of protection. For the treatment of surfaces or materials, the concentration of a sulfur-containing quaternary ammonium ionene polymer according to the present invention preferably ranges from about 0.01 to 0.5 ppm (w / w); more preferably from 0.01 to 0.1 ppm, and most preferably from 0.01 to 0.025 ppm in the applied composition.

In aqueous systems, a preferred effective amount of active compound ranges from 0.05 to 5,000 ppm, and most preferably, from 0.05 to 1,000 ppm of the aqueous system. The amount of sulfur-containing quaternary ammonium ionene polymer effective to prevent the formation of sludge in an aqueous liquid preferably ranges from 10 to 100 ppm, and more preferably from 5 to 25 ppm of the aqueous liquid.

To illustrate the nature of the invention, the following examples are set forth. It is to be understood, however, that the invention is not limited to the specific conditions or details set forth in these examples. 11

Example 1

Preparation of ethylene (dimethyliminio) ethylene- (dimethyliminio) ethylene] To a 110 mL round bottom flask with a reflux condenser, magnetic stirrer, and N 2 atmosphere was added 11.5 g (TMEDA), 15.8 g of 2,2'-dichlorodiethyl sulfide (Mustard Gas), and 25 ml of H2 O. This dispersion was then mixed and heated at 60 ° C for 8 hours. The solution gradually turned a reddish tint and the reaction mixture was then cooled to room temperature.

Example 2

Preparation of poly [sulfoxy-ethylene (dimethyliminio) ethylene- (dimethyliminio) ethylene] To a 100 mL round bottom flask with a reflux condenser, magnetic stirrer, and N 2 atmosphere was added 11.5 g (TMEDA), 15.8 g of 2,2'-dichlorodiethyl sulfide (Mustard gas), and 25 ml of H 2 O. This dispersion was then mixed and heated at 60 ° C for 8 hours. The solution gradually turned a reddish tint and the reaction mixture was then cooled to room temperature. Slow addition of 11.3 g of 30% hydrogen peroxide was added such that the temperature never exceeded 60øC. The solution was recooled to room temperature after a short mixing time to give a 51% by weight polymer solution.

Example 3 The polymer produced in Example 1 was studied to determine its potential carcinogenicity using a 12

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of Ames current. Table 1 presents the test results against a list of organisms used in the Ames mutagenicity test. TABLE 1

Organism TA 98 TA 100 * TA 1535 TA 1537

Test result

Negative response Negative response

Slightly positive Negative response * Confirmation test for this strain was inconclusive.

Example 4

Preparation of poly [thioethylene (diethyliminio) ethylene- (dimethylimmonium) ethylene], (Compound 1).

A solution of 17.4 g of TMEDA (0.15 mol), 23.85 g of 2,2'-dichlorodiethyl sulfide (0.15 mol), and 25.76 g of water were prepared in a reactor. The contents were heated at 60 ° C for seven and a half hours, with continuous mixing. After two hours the contents were in a single aqueous phase. The reactor was then allowed to cool to room temperature. The polymer-in-water solution product was diluted to an appropriate concentration and used in the Examples below.

Example 5

Preparation of poly [sulfoxyethylene (dimethylimino) ethylene- (dimethyliminio) ethylene], (Compound 2).

A solution of 17.4 g of TMEDA (0.15 mol), 23.85 g of 2,2'-dichlorodiethyl sulfide (0.15 mol), and 25.76 g of water were prepared. The contents of the reactor were heated to 60øC for 7 ½ hours with continuous mixing. After two hours the contents were in a single aqueous phase. The reactor was then allowed to cool to room temperature.

17.0 g of a 30% solution of hydrogen peroxide were then added portionwise to the reaction flask. After four hours, a standard starch / iodine peroxide test indicated a negative result. The polymer-in-water solution product was diluted to an appropriate concentration and used in the Examples below.

The effect of sulfur-containing quaternary ammonium ionene polymers on Enterobacter aerogenes and / or Pseudomonas aeruginosa bacteria and the effect on algae were determined using the method described in U.S. Patent 2,881,070 (the disclosure of which is hereby incorporated by reference) . The results are described in Table 2 and Table 3. TABLE 2

Concentration in parts per million (ppm) required for 90% or more death by ionene polymers, Compounds 1 and 2, against bacteria Enterobacter aerogenes and Pseudomonas aeruginosa at pH 6 and pH 8 on a substrate of basal salts after 18 hours contact. Compound Bacteria pH 6 PH 8 1 Enterobacter aerogenes 0.5 0.05 or less 1 Pseudomonas aeruginosa 0.7 0.5 2 Enterobacter aerogenes 0.7 0.5 14 - u K-- TABLE 3

Minimum Inhibitory Concentration of Ionene Polymers Compound 1 and 2 in parts per million (ppm) against algae Chlorella pyrenoidosa, Chlorococcum hypnosporum and Oscillatoria proliferates at pH 7 on a basal salt substrate after 28 days of contact Alqa Compound 1 Compound 2 Chlorella pyrenoidosa 5 , 0 2.0 Chlorococcum hypnosporum 1.0 2.0 Oscillatoria proliferates 5.0 1.0

Example 7

Determination of the Inhibition Zone of the Ionene Polymer Compound 1 Against Various Fungi The technique used was a standard agar diffusion method in which the biological activity of the test chemical is expressed as a zone of inhibition around the point of application. In the test, paper disks (diameter 6 mm) were immersed in aqueous solutions of the ionene polymer, respectively containing 103, 104, and 105 ppm of the active principle. After a brief air drying the treated discs were placed in the center of freshly scratched potato dextrose agar plates with one of the various species of organisms listed in Table 3. After incubation for ten days the zone diameters were determined, the results being listed in Table 4.

t TABLE 4

Zone of inhibition, in millimeters, of Aspergillus niger, Trichoderma harzianum, Penicillium roqueforti, and Aureobasidium pullulans as a function of the ionene polymer concentrations used.

Ionene concentration (ppm): 103 104 105 Orqanism! Area diameter (mm) Aspergillus niger 0 0 18 Trichoderma harzianum 0 0 6 Penicillium roqueforti 8 14 25 Aureobasidium pullulans 0 10 15

Example 8 The efficacy of the sulfur containing quaternary ammonium ionene polymer compositions as contact disinfectants in short contact suspension tests was examined using a mixed bacterial population consisting of Staphylococcus aureus, Enterobacter aerogenes and Pseudomonas aeruginosa. Each microorganism was grown on tryptone and glucose agar extract (TGEA) and harvested after 24 hours. A bacterial suspension was prepared in physiological saline with each organism and adjusted with the aid of a McFarland # 1 turbidity standard to equal approximately 1.0 × 10 4 cells / ml. Equal portions of each adjusted bacterial suspension were mixed and used as the inoculum. On the day of the test a stock solution of the biocide was freshly prepared (1%) and diluted to the desired concentration in sterile distilled water. Ten (10.0) milliliters of the diluted biocide were placed in sterile test tubes and 20 microliters of the inoculum was introduced and the time was counted for exactly 10.0 minutes. After exposure, each 1.0 milliliter was transferred to 9 milliliters of a deactivating solution of the biocide. After quenching, a ten-fold dilution series was prepared in 9 ml of physiological serum 16 whites. Bacterial survival was assessed by the current plating technique using TGEA. All plates were incubated at 37 ° C for 48 hours and counted. Controls were treated analogously with the exception that no biocide was used, only sterile distilled water.

The results are shown below in Table 5. Both compounds 1 and 2 have equal or better rapid antibacterial action than Benzalkonium chloride (Ben.Cl), a quaternary ammonium salt commonly used for cleaning and disinfection. TABLE 5

(Ppm) 50 100 250 500 1 99.91 99.93 99.93 99.95 99.98 99.99 Compound Concentration (ppm) Compound 1 99.99 99.98 2 96.99 97.47 97.15 98.53 Ben.Cl 83.44 86.29 99.68 99.99 Lisbon / September 28, 2000

0. OFFICIAL AGGREGATE OF INDUSTRIAL PROPERTY

17

Claims (4)

V u A microbicidal composition comprising an aqueous solution of a sulfur-containing quaternary ammonium ionene polymer comprising a repeating unit of formula II: R1 -B-A-B-. 2X R2 (II) wherein X2 is a counterion; R 1 and R 2, which may be the same or different, are selected from a C 1 -C 4 alkyl group and -CH 2 -CH 2 -OH; A 'is a radical selected from -S-, -S-CH 2 -CH 2 -S-, -S-S- and the oxidation products of -S-, -S-? CH 2 CH 2 -S- and -S-S-; and B is a radical selected from C 1 -C 5 alkyl, -CH 2 -CH (OH) -CH 2 -, and - (CH 2) m -O- (CH 2) m -, wherein each m is independently 1, 2 or 3, and wherein the sulfur-containing quaternary ammonium ionene polymer is present in an amount effective to inhibit the growth of at least one microorganism. The composition of claim 1 wherein A 'is selected from -S-, and the oxidation products -SO-, -SO 2 - and -SO 2 -S-. The composition of claim 2 wherein the quaternary ammonium ionene polymer is selected from poly [ethylene (dimethylimino) ethylene (dimethylimino) ethylene] and poly [sulfoxyethylene (dimethylimino) ethylene- (dimethylimino) )-ethylene]. A method for inhibiting the growth of microorganisms or algae in an aqueous system comprising the step of adding to an aqueous system known to be required such inhibition of the microbicidal composition according to any of claims 1 to 3. Method for inhibiting the formation of sludge in a system aqueous composition comprising the step of adding to an aqueous system known to be in need of such inhibition of the microbicidal composition according to any one of claims 1 to 3. A method for inhibiting the growth of microorganisms on the surface of a substance comprising the surface admixture step inhibiting the microbicidal composition according to any one of claims 1 to 3. A method according to claim 4 or claim 5 wherein the aqueous system is a metal working fluid. The method of claim 4 or claim 5 wherein the quaternary ammonium polymer is present in an amount in the range of from 0.05 to 5,000 ppm of the aqueous system. A method according to claim 6 wherein the substance is wood, paper, leather, a seed or a painted surface. A method according to claim 6 wherein the quaternary ammonium polymer is present in an amount ranging from 0.01 to 0.5 ppm (w / w). Lisbon, 28 September 2000 0 OFFICIAL AGENT OF INDUSTRIAL PROPERTY 3